First post, please let me know if I've made any mistakes in asking my question.
I'm trying to write a bootloader for a device using a STM32u585ZIT chip. When booting, it will read a partition table saved in flash to determine if it will boot from partition A (Address 0x08080000) or partition B (Address 0x08180000). I have decided on using the BANK_SWAP option byte to swap the addresses of these partitions so that I only need to write a single linker script for the application code.
Here is the code I'm using to set the swap bit if we want to boot from partition B:
if ((partitions.a == partitionStatusUpdate)
|| ((partitions.a == partitionStatusActive)
&& (partitions.b != partitionStatusUpdate))) {
printf("Booting partition A\n");
} else if ((partitions.b == partitionStatusUpdate)
|| ((partitions.b == partitionStatusActive)
&& (partitions.a != partitionStatusUpdate))) {
if (HAL_FLASH_Unlock() != HAL_OK) {
printf("Could not unlock flash!\n");
NVIC_SystemReset();
}
if (HAL_FLASH_OB_Unlock() != HAL_OK) {
printf("Could not unlock flash option bytes!\n");
NVIC_SystemReset();
}
FLASH->OPTR |= FLASH_OPTR_SWAP_BANK;
if (HAL_FLASH_OB_Lock() != HAL_OK) {
printf("Could not lock flash!\n");
NVIC_SystemReset();
}
if (HAL_FLASH_Lock() != HAL_OK) {
printf("Could not lock flash option bytes!\n");
NVIC_SystemReset();
}
}
From what I gather from reference documents this should swap the banks' addresses, so I should only ever need to tell it to access the application at 0x08080000 after this point. However, using the following code (APP_ACTIVE_ADDR == 0x08080000):
appAddress = (uint32_t*) APP_ACTIVE_ADDR + 1;
GoToApplication = (pFunction) *appAddress;
__set_MSP(*(uint32_t*) APP_ACTIVE_ADDR);
SCB->VTOR = APP_ACTIVE_ADDR;
GoToApplication();
I am finding it only ever boots app A.
I have searched around and found people asking similar questions regarding different chips, but the only question referring to the U5 specifically is this one, but I don't think the answer there is relevant to me because the original poster was using two separate linker scripts:
https://community.st.com/t5/stm32cubeprogrammer-mcus/mb1549c-swapbank-is-set-1-but-its-not-run-bank2-firmware-always/td-p/57235
I assume I am missing some steps to make this work, but I cannot figure out what they are. Can anyone help? Please let me know if any extra information is required or if I have been unclear about anything.
